| Population | Risk Signal | Evidence Level | Key Consideration | Clinical Verdict |
|---|---|---|---|---|
| Gallbladder Stones | ↑ Increased Risk | Meta-analysis of 76 RCTs | RR 1.37 for biliary disease; dose-dependent | Use with caution; consider UDCA prophylaxis |
| Cirrhosis of Liver | ↓ Potential Benefit | Cohort studies; Phase 2 trials | Protective in pre-cirrhotic MASLD; limited data in decompensated | Consider in compensated cirrhosis; avoid in decompensated |
| ESRD / Dialysis | ⚠ Limited Data | Small retrospective studies | Dulaglutide & semaglutide not renally cleared; GI side effects amplified | Likely safe; cautious use; KDIGO supports consideration |
| Diabetic Retinopathy | ⚠ Transient Worsening | SUSTAIN-6; multiple meta-analyses | Early worsening linked to rapid HbA1c drop, not drug per se | Pre-treatment eye screening; stabilise retinopathy before starting |
| NAION Risk | ↑ Emerging Signal | Retrospective cohorts; EMA review 2025 | Semaglutide: pooled HR 2.62; EMA now lists as very rare ADR | Counsel patients; assess disc-at-risk; stop if NAION confirmed |
| Elderly ≥75 years | ⚠ Sarcopenia Concern | Sub-analyses; limited RCT data in ≥75 | 15–40% of weight lost may be lean mass; increased frailty risk | Individualise; high-protein diet; resistance exercise; slow titration |
| Severe Heart Failure (HFrEF) | ⚠ Potential Harm | FIGHT trial (liraglutide); LIVE trial | Neutral-to-harmful in HFrEF; beneficial in HFpEF (STEP-HFpEF) | Avoid in NYHA III–IV HFrEF; beneficial in obesity-related HFpEF |
| Advanced Dementia | ⚠ Practical Concern | Observational; ELAD trial (Phase 2b) | Neuroprotective signals in early dementia; oral intake issues in advanced | Not appropriate in advanced dementia; promising for MCI/early AD |
| Pregnancy | ✘ Contraindicated | Animal studies; observational cohorts | Not licensed; stop 2 months before conception (semaglutide) | Contraindicated; discontinue pre-conception; use contraception |
| Type 1 Diabetes | ⚠ Off-Label | ADJUNCT ONE/TWO; consensus report 2024 | Weight loss + ↓ insulin dose; ↑ DKA risk if insulin over-reduced | Off-label with specialist supervision; reduce bolus 25–33% |
GLP-1 receptor agonists have been consistently associated with an increased risk of gallbladder disease, including cholelithiasis and cholecystitis. This risk is amplified with higher doses, longer treatment duration, and when used primarily for weight loss rather than glycaemic control.
He et al. — JAMA Internal Medicine (2022)
Systematic review and meta-analysis of 76 RCTs involving 103,371 patients. GLP-1 RA treatment was associated with a 37% higher relative risk of gallbladder or biliary diseases compared with controls.
RR 1.37 (95% CI: 1.23–1.52)Risk Amplification in Obesity Indication
In trials specifically for weight loss (n=13), the risk was substantially higher with RR 2.29, versus RR 1.27 in diabetes/other disease trials (P<0.001 for interaction). The absolute risk increase was approximately 27 additional events per 10,000 patients per year.
RR 2.29 (95% CI: 1.64–3.18) for weight-loss indicationFrontiers in Pharmacology (2025)
Pharmacovigilance analysis of FAERS database (Q1 2004 – Q2 2024). Significant disproportionality signals were detected for cholecystitis and cholelithiasis across multiple GLP-1 RAs including exenatide, liraglutide, semaglutide, dulaglutide, and tirzepatide.
Median onset: variable by agent and age groupComparative Risk by Agent
LEADER trial: liraglutide showed HR 1.60 (95% CI: 1.23–2.09) for acute gallbladder/biliary disease. Tirzepatide appears relatively safer among GLP-1 RAs for gallbladder outcomes, though still associated with composite biliary disease risk.
Liraglutide HR 1.60; Tirzepatide — lower but not zero risk🔬 Pathophysiological Mechanisms
GLP-1 RAs promote gallstone formation through multiple converging pathways: (1) Suppression of cholecystokinin (CCK) secretion, reducing gallbladder contractility and promoting bile retention; (2) Altered TGR5 signalling, decreasing cAMP-mediated gallbladder relaxation; (3) Disruption of FXR signalling, reducing FGF19 production and dysregulating bile acid synthesis via CYP7A1 and BSEP; (4) Alteration of vagal nerve signalling through GLP-1R in the NTS and area postrema, causing asynchronous gallbladder contractions. Rapid weight loss further supersaturates bile with cholesterol.
🩺 Clinical Practice Recommendations
- Screen for pre-existing gallbladder disease before initiating GLP-1 RA, especially in high-risk patients (female, obesity, rapid weight loss, multiparity)
- Educate patients on symptoms of cholecystitis (RUQ pain, fever, nausea post-fatty meals)
- Consider prophylactic ursodeoxycholic acid (UDCA) 300 mg BD in patients undergoing rapid weight loss (>1.5 kg/week)
- Use slow dose titration to minimise rate of weight loss
- Abdominal ultrasound if biliary symptoms develop; lower threshold for cholecystectomy referral
- Post-cholecystectomy patients can generally continue GLP-1 RA therapy
GLP-1 RAs represent a promising therapeutic class across the spectrum of metabolic dysfunction-associated steatotic liver disease (MASLD). While they have demonstrated the ability to reverse steatohepatitis and reduce cardiovascular risk in patients with MASLD with or without fibrosis, their role in established cirrhosis requires careful distinction between compensated and decompensated disease.
Kanwal et al. — VA Cohort Study (n=32,116)
In patients with MASLD and diabetes without cirrhosis, GLP-1 RA use was associated with lower risk of progression to cirrhosis, cirrhosis complications, and all-cause mortality vs DPP-4 inhibitor use. Semaglutide showed strongest signal.
HR 0.78 for cirrhosis progression; 22% ↓ complicationsYen et al. — Taiwan National Database (n=934)
In patients with T2D and compensated cirrhosis, GLP-1 RA users had significantly lower risks of mortality (aHR 0.47), cardiovascular events (aHR 0.60), decompensated cirrhosis (aHR 0.70), hepatic encephalopathy (aHR 0.59), and liver failure (aHR 0.54).
aHR 0.47 (95% CI: 0.32–0.69) for mortalitySemaglutide in Compensated MASH Cirrhosis
In a phase 2 trial, semaglutide did not significantly improve fibrosis in compensated MASH cirrhosis, but provided meaningful improvements in weight, glycaemic control, and was well tolerated with cardiovascular benefits through metabolic improvements.
Fibrosis endpoint not met; metabolic benefits confirmedGLP-1 RA in MASLD — 7-Year Outcomes
Large retrospective cohort (TriNetX) showed GLP-1 RA use in MASLD patients was associated with reduced risk of heart failure (HR 0.72), portal hypertension events (HR 0.46), and all-cause mortality (HR 0.30) at 7 years.
HR 0.30 (95% CI: 0.24–0.39) for mortality at 7 years⚠ Critical Distinction
Compensated vs Decompensated Cirrhosis: The protective association was NOT seen in patients with existing cirrhosis in the Kanwal et al. VA study (HR 1.18 for cirrhosis complications, non-significant). Concerns about muscle mass loss in sarcopenic cirrhotics, GI intolerance with portal hypertension, and the risk of hepatic decompensation with rapid weight loss must be weighed carefully. GLP-1 RAs are NOT metabolised by the liver, but there are theoretical concerns about reduced appetite worsening malnutrition in advanced cirrhosis.
🩺 Clinical Practice Recommendations
- Strong consideration for GLP-1 RA use in MASLD/MASH pre-cirrhotic stages to prevent progression
- Reasonable to use in compensated cirrhosis (Child-Pugh A) with T2D — emerging data supports benefit
- Avoid in decompensated cirrhosis (Child-Pugh B/C) — insufficient evidence, malnutrition/sarcopenia concerns
- Monitor nutritional status and lean body mass in cirrhotic patients
- Slow titration essential; GI side effects may be less tolerable with gastropathy
Although GLP-1 RAs have demonstrated significant renoprotective benefits in earlier stages of CKD (FLOW trial with semaglutide), their use in ESRD (eGFR <15 mL/min/1.73 m²) and in patients on dialysis remains an area of limited but growing evidence. Critically, most GLP-1 RAs are not renally cleared, supporting their pharmacokinetic safety in this population.
Semaglutide in CKD + T2D
FLOW trial (stopped early for efficacy) demonstrated semaglutide significantly slowed CKD progression and reduced kidney failure risk in T2D patients with CKD. However, patients with eGFR <15 and those on dialysis were excluded.
24% ↓ primary kidney composite endpointGLP-1 RA Use in ESRD — Real-World
Single-centre VA study of 46 patients with ESRD (mean eGFR 20) on GLP-1 RA. Baseline HbA1c 8.2% improved meaningfully. 59% were on haemodialysis. The study concluded GLP-1 RAs were likely safe and effective, consistent with KDIGO guidelines.
Likely safe per KDIGO recommendationGLP-1 RA Safety in Advanced CKD/ESKD
Meta-analysis of clinical trials and cohort studies in CKD stage 5/ESKD. GLP-1 RAs showed improved glycaemic control and weight loss; no excess mortality or serious adverse events. Predominantly Asian populations; short follow-up.
No excess serious adverse events vs controlsUKRPG Guidance Statement
UK Renal Pharmacy Group states: "Reduced kidney function does not affect the safety or tolerability of GLP-1 RAs." These medicines can be prescribed safely including in those on dialysis and post-transplant, as they are not metabolised by the kidney. Standard dosing applies.
No dose adjustment required in CKD/ESRD🩺 Clinical Practice Recommendations
- Semaglutide and dulaglutide do not require dose adjustment in CKD/ESRD
- KDIGO 2024 guidelines support GLP-1 RA use in T2D with CKD as a priority treatment
- GI side effects (nausea, vomiting) may be amplified in uraemic patients — very slow titration recommended
- Monitor for dehydration risk, especially in patients on dialysis with limited oral intake
- Exenatide (if still available) should be avoided in eGFR <30 (renally cleared)
- Consider GLP-1 RA as a safer alternative to insulin in the high-hypoglycaemia-risk ESRD population
The association between GLP-1 RAs and diabetic retinopathy (DR) worsening has generated significant clinical debate since the SUSTAIN-6 trial. The prevailing scientific consensus is that this represents an "early worsening" phenomenon — a transient paradoxical deterioration driven by rapid glycaemic improvement rather than a direct toxic effect of GLP-1 RAs. This same phenomenon was observed with insulin intensification in the DCCT trial and after bariatric surgery.
Semaglutide Cardiovascular Outcome Trial
Retinopathy complications (vitreous haemorrhage, blindness, need for intravitreal/photocoagulation) occurred in 3.0% of semaglutide vs 1.8% of placebo groups. This resulted in the FDA label warning for semaglutide products.
HR 1.76 (95% CI: 1.11–2.78); P=0.02Bethel et al. — CVOT Meta-Regression
Meta-analysis of multiple CVOTs found that HbA1c reduction magnitude was significantly correlated with retinopathy risk. This supports the hypothesis that rapid glycaemic improvement — not the drug class itself — drives the risk.
Risk correlates with ΔHbA1c, not agent specificityCole Eye Institute Retrospective Study
~1,000 patients with T2D (700 on GLP-1 RA, 300 on SGLT2i). After granular manual review of each case, no association was found between GLP-1 RA use and worsening DR. Initial coding suggested worsening, but was not confirmed on clinical review.
No true DR worsening on detailed clinical reviewAnimal Models — Neuroprotection
Paradoxically, animal models consistently show GLP-1 RAs have neuroprotective effects on the retina — preventing DR progression, showing anti-inflammatory properties, and enhancing vascular architecture. GWAS data also shows GLP1R gene variants inversely associated with severe NPDR (OR 0.72).
Retinal neuroprotection in preclinical models⚡ Risk Factors for Early Worsening of DR with GLP-1 RAs
- Greater magnitude of HbA1c reduction (the key driver)
- Poor baseline glycaemic control (high starting HbA1c)
- Longer duration of diabetes
- Pre-existing moderate-to-severe DR or PDR at baseline
- Concurrent insulin use at initiation
- Speed of HbA1c reduction (rapid drop)
- Older patient age
🩺 Clinical Practice Recommendations
- Obtain baseline ophthalmological assessment before starting GLP-1 RA in patients with diabetes
- Treat any sight-threatening DR (PDR/CSME) BEFORE or concurrently with GLP-1 RA initiation
- Gradual dose titration to prevent rapid HbA1c drop — aim for 0.5–1% per 3 months
- More frequent retinal screening (3–6 monthly) in first year for high-risk patients
- Do NOT withhold GLP-1 RA in patients with stable/mild DR — benefits outweigh transient risk
- Close collaboration between endocrinologist and ophthalmologist
NAION is a rare but serious cause of irreversible vision loss characterised by sudden, painless, monocular visual field defects. A growing body of evidence has linked semaglutide specifically to an increased risk of NAION, culminating in the EMA's PRAC concluding in June 2025 that NAION is a very rare side effect of semaglutide (affecting up to 1 in 10,000 users), with product labelling updates recommended.
Hathaway et al. — Massachusetts Eye & Ear
Retrospective matched cohort (n=16,827). Cumulative 36-month NAION incidence: semaglutide 6.7% vs non-GLP-1 RA 0.8%. Cox regression showed significantly elevated risk with semaglutide.
HR 7.64 (95% CI: 2.21–26.36); P<0.001Pooled Analysis of 10 Studies
Meta-analysis of 10 research articles on semaglutide and NAION. Pooled HR of 2.62 (P<0.001). Risk becomes statistically significant after 2 years. Semaglutide accounted for 86.5% of all GLP-1 RA-associated NAION reports. Clinical features: disc oedema, crowded disc.
Pooled HR 2.62 (95% CI: 1.81–3.80)Simonsen et al. — National Cohort
Nationwide study from Denmark and Norway confirmed the association. Pooled HR 2.81 (95% CI: 1.67–4.75). The absolute risk increase was +1.41 NAION events per 10,000 person-years — i.e., a very rare event in absolute terms.
IRD: +1.41 per 10,000 person-years (very rare)PRAC Conclusion & WHO Alert
EMA's PRAC concluded NAION is a very rare side effect of semaglutide (Ozempic, Rybelsus, Wegovy). Product information to be updated. WHO issued a safety alert in June 2025. If NAION confirmed, treatment should be stopped.
Very rare ADR: up to 1 in 10,000 users (EMA)⚠ Key Risk Factors for NAION with Semaglutide
Older age, male sex, prolonged diabetes duration, elevated HbA1c, pre-existing diabetic retinopathy, obesity, obstructive sleep apnoea, systemic hypertension, and crucially — a "disc at risk" (crowded optic disc with small cup-to-disc ratio), which is the strongest anatomical risk factor and can be detected on routine eye examination.
🩺 Clinical Practice Recommendations
- Counsel patients about the very rare risk of sudden painless vision loss before initiating semaglutide
- Baseline eye examination to identify "disc at risk" (small cup-to-disc ratio) — especially in older patients
- Patients should report any sudden visual changes immediately
- If NAION is confirmed, discontinue semaglutide (per EMA recommendation)
- Data on other GLP-1 RAs is more limited; signal appears strongest with semaglutide
- NAION is not yet listed as a contraindication — it is a very rare side effect to balance against cardiovascular benefits
Adults over 75 represent a particularly under-studied population in GLP-1 RA trials — fewer than 3% of clinical trial participants were aged ≥75. Key concerns centre on sarcopenia exacerbation (15–40% of weight lost may be lean mass), frailty progression, malnutrition risk, and GI intolerance. However, emerging data in those aged ≥80 suggest cardiorenal benefits that may outweigh risks in selected patients.
Sarcopenia Risk in Older Adults
Adults over 65 have 12–16% natural skeletal muscle mass decline. Up to half of adults over 80 experience sarcopenia. A 2024 review found 15–60% of weight lost on GLP-1 RAs may come from lean mass. Weight cycling (stop-start) may further worsen sarcopenic obesity.
15–60% of weight loss may be lean body massGLP-1 RA in Patients ≥80 Years — TriNetX
Retrospective cohort study (TriNetX database) examining cardiorenal outcomes in patients ≥80 with T2D. GLP-1 RA users showed favourable cardiorenal outcomes vs DPP-4i users, suggesting benefit even in the very elderly if appropriately selected.
Cardiorenal benefit demonstrated in ≥80 age group🩺 Clinical Practice Recommendations
- Individualised risk-benefit assessment; avoid in frail, underweight, or patients with advanced dementia/reduced oral intake
- Start at lowest dose; very slow titration (double the standard titration intervals)
- Mandatory: high-protein diet (≥1.2 g/kg/day) and resistance exercise programme
- Monitor body composition if possible (DEXA or bioimpedance) rather than weight alone
- Target weight loss goal of 5–10% maximum (not >15%) in the elderly
- Higher threshold for GI side effect management — consider anti-emetics proactively
- Screen for sarcopenia (grip strength, gait speed) before and during treatment
- GLP-1 RA may be particularly valuable for cardiovascular/renal risk reduction in robust elderly patients
The relationship between GLP-1 RAs and heart failure is nuanced and phenotype-dependent. While these agents prevent new-onset HF and show striking benefits in obesity-related heart failure with preserved ejection fraction (HFpEF), they have demonstrated neutral-to-harmful effects in patients with established heart failure with reduced ejection fraction (HFrEF). This critical distinction is often inadequately reflected in clinical guidelines.
STEP-HFpEF & STEP-HFpEF DM Trials
Semaglutide 2.4 mg weekly in patients with obesity-related HFpEF demonstrated significant improvements in heart failure symptoms, physical limitations, exercise capacity, and reduced HF events. Pooled analysis (n=1,145) showed consistent benefits.
Significant improvement in KCCQ-CSS & 6MWDFIGHT Trial — Liraglutide in Advanced HFrEF
Liraglutide in recently hospitalised HFrEF patients (LVEF ≤40%, NYHA II–IV) showed no benefit. A meta-analysis of FIGHT + EXSCEL found a 1.5-fold increase in the odds of HF hospitalisation in HFrEF patients randomised to GLP-1 RA vs placebo.
OR 1.5 for HF hospitalisation in HFrEF (FIGHT + EXSCEL)Neutral/Harmful in Established HFrEF
The LIVE trial tested liraglutide in stable HFrEF. Results were neutral for LVEF improvement but showed concerning increases in heart rate and serious cardiac adverse events in the liraglutide arm. NYHA class IV was an exclusion criterion in LEADER and SUSTAIN-6.
Increase in heart rate & serious cardiac eventsPrevention vs Treatment of HF
Meta-analyses of CVOTs show GLP-1 RAs reduce incident HF hospitalisation in T2D at high CV risk, but this does not extend to treatment of established HFrEF. The HF prevention benefit is primarily driven by weight loss, BP reduction, and anti-atherosclerotic effects.
Prevents new-onset HF ≠ treats established HFrEF🩺 Clinical Practice Recommendations
- HFpEF with obesity: Strong indication for semaglutide — significant symptom and functional improvement
- HFrEF (LVEF ≤40%): Avoid GLP-1 RAs, especially in NYHA III–IV. Use SGLT2 inhibitors instead (proven benefit)
- NYHA class IV was an exclusion criterion in major CVOTs — no safety data in this population
- If GLP-1 RA needed for T2D/obesity in mild HFrEF (NYHA II), use with caution and close monitoring
- Monitor heart rate (GLP-1 RAs increase HR by ~2–4 bpm) — relevant in HF
- SGLT2 inhibitors remain the preferred cardiometabolic agent in HFrEF
GLP-1 RAs represent one of the most exciting emerging areas in neurodegeneration research. GLP-1 receptors are present in the CNS, and GLP-1 RAs can cross the blood-brain barrier. Epidemiological data consistently show 30–70% lower dementia risk in GLP-1 RA users vs other antidiabetic agents. The ELAD trial demonstrated liraglutide's safety in mild AD. However, in advanced dementia, practical concerns (reduced oral intake, swallowing difficulties, GI intolerance, inability to report adverse effects) limit their applicability.
Liraglutide in Mild-Moderate AD (Phase 2b)
204 patients with mild-moderate AD (non-diabetic), 52-week liraglutide vs placebo. Primary endpoint (cerebral glucose metabolism) was not met. However, cognitive decline was reduced by ~18%. Liraglutide was safe and well tolerated in this population.
~18% reduction in cognitive decline; safe profileSemaglutide/Tirzepatide & Neurodegeneration
Large retrospective study in T2D with obesity found semaglutide and tirzepatide associated with lower risks of dementia, stroke, and all-cause mortality. Dementia risk reduced with semaglutide; stroke risk reduced with tirzepatide.
HR ≤0.69 for AD risk with GLP-1 RA initiationGLP-1 RAs in Ischemic Stroke
Meta-analyses of CVOTs demonstrate consistent reduction in non-fatal stroke with GLP-1 RAs. Multiple mechanisms: vascular risk modification, anti-inflammation, endothelial function improvement. Trials in acute stroke ongoing (TEXAIS, GALLOP, ASSET).
Consistent ↓ non-fatal stroke across CVOTsSemaglutide in Early AD — Phase 3
The EVOKE/EVOKE Plus studies are the largest trials ever conducted with a GLP-1 RA (semaglutide) in Alzheimer's disease, enrolling ~1,800 patients with early AD. Results anticipated late 2025 — potentially transformative for the field.
Phase 3: ~1,800 patients; results anticipated 2025⚠ Advanced Dementia — Practical Contraindications
In patients with advanced dementia: reduced oral intake may worsen with appetite suppression; inability to report GI symptoms, hypoglycaemia, or visual changes; risk of dehydration from vomiting; goals of care typically shift to comfort. GLP-1 RAs are not appropriate in advanced dementia. In severe stroke with dysphagia: injectable GLP-1 RAs remain administrable, but metabolic goals should be conservative and aspiration risk from vomiting must be considered.
🩺 Clinical Practice Recommendations
- Mild cognitive impairment / Early AD: Consider GLP-1 RA for cardiometabolic indications — potential added neuroprotective benefit
- Advanced dementia: Generally not appropriate — prioritise comfort, adequate nutrition, and simplification of medication regimen
- Post-stroke: GLP-1 RAs are appropriate for secondary cardiovascular prevention in recovered stroke patients with T2D/obesity
- Acute stroke: Ongoing trials (TEXAIS, GALLOP); not current standard of care
- Consider injectable rather than oral formulations in patients with mild swallowing difficulties
No GLP-1 RA is currently approved for use during pregnancy or in women planning to become pregnant. Animal studies have shown dose-dependent reductions in fetal weight, skeletal ossification abnormalities, and embryonic death at supratherapeutic doses. However, the limited human data available do not indicate an increased pattern of congenital malformations from inadvertent first-trimester exposure. This is an area of rapidly evolving evidence as prescriptions in women of reproductive age increase.
Cesta et al. — Multi-Country Cohort
Population-based study from 4 Nordic countries, US, and Israel. 938 pregnancies exposed to GLP-1 RAs periconceptionally. No significantly increased risk of major congenital malformations vs insulin (adjusted RR 0.95; 95% CI: 0.72–1.26).
aRR 0.95 (95% CI: 0.72–1.26) — No increased MCM risk vs insulinDao et al. — 6 Teratology Services
168 pregnancies exposed to GLP-1 RAs in early pregnancy (mostly liraglutide and semaglutide). No specific pattern of birth defects identified. MCM rate 2.6% — comparable to diabetes reference group (2.3%) and overweight/obese group (3.9%).
MCM 2.6% — No specific malformation patternUK Teratology Information Service
UKTIS states: "Limited data do not indicate that GLP-1 RA use in early pregnancy is associated with increased risk of miscarriage, malformation, stillbirth, low birth weight or preterm delivery." Inadvertent exposure is NOT grounds for termination. GLP-1 RAs have high molecular weight; placental transfer not expected.
Not grounds for termination of pregnancy (UKTIS)Washout Period Recommendations
Semaglutide: Discontinue at least 2 months before planned pregnancy. Tirzepatide: Discontinue at least 1 month before. Liraglutide: No specific wash-out period specified but discontinue when pregnancy confirmed. All agents: contraception essential during treatment.
Semaglutide: ≥2 months washout; Tirzepatide: ≥1 month⚠ The "Ozempic Baby" Phenomenon
GLP-1 RA-induced weight loss can restore ovulatory cycles in women with PCOS and oligomenorrhoea, leading to unplanned pregnancies in women previously believed to be infertile. This "Ozempic baby" phenomenon means pre-conception counselling and contraception are mandatory when prescribing GLP-1 RAs to women of reproductive age. The risk of inadvertent early pregnancy exposure is increasing substantially as prescriptions expand.
🩺 Clinical Practice Recommendations
- GLP-1 RAs are contraindicated in pregnancy — not licensed for use
- Discuss contraception at every consultation with women of reproductive age on GLP-1 RA
- Pre-conception counselling should include planned discontinuation of GLP-1 RA with appropriate washout
- If inadvertent exposure occurs: reassure — current data do not show increased MCM risk; not grounds for termination
- Refer to specialist fetal medicine/teratology service for individualised counselling after inadvertent exposure
- Switch to insulin for glycaemic management in pregnancy (per NICE/ADA guidelines)
GLP-1 RAs are not FDA/MHRA approved for type 1 diabetes. However, with the rising prevalence of obesity in T1D (affecting up to 30–50% of adults) and the difficulty in achieving glycaemic targets even with AID systems, there is growing interest and off-label use of GLP-1 RAs as insulin adjuncts. The ADA's 2023 Standards of Care acknowledged the potential off-label application. A 2024 Diabetes Technology Society consensus report provides the most comprehensive expert guidance to date.
Liraglutide as Adjunct to Insulin in T1D
ADJUNCT ONE (n=1,398, 52 weeks) and ADJUNCT TWO (n=835, 26 weeks) tested liraglutide added to insulin in T1D. Showed HbA1c reduction (~0.3–0.5%), weight loss, and insulin dose reduction. However, increased rates of hypoglycaemia and ketosis events were reported.
↓ HbA1c 0.3–0.5%; ↓ weight; but ↑ hypo & ketosisDiabetes Technology Society — GLP-1 RA + AID in T1D
Expert consensus from 3 virtual meetings (2024) synthesised evidence on GLP-1 RA as adjunct to automated insulin delivery in adults with T1D. Concluded that GLP-1 RAs combined with AID offer promising improvements in glycaemia, weight, and insulin requirements, but require mandatory insulin dose reduction protocols.
Bolus insulin reduced 25–33%; Basal reduced 10–25%GLP-1 RA Outcomes in T1D — Meta-Analysis
Semaglutide and tirzepatide groups showed 5.4% and 14% weight loss respectively. HbA1c improved without increasing severe hypoglycaemia risk when combined with appropriate insulin adjustments. No statistically significant difference in efficacy between semaglutide and tirzepatide.
Tirzepatide: 14% weight loss in T1DDiabetic Ketoacidosis (DKA) Risk
The critical safety concern is euglycaemic DKA if insulin is over-reduced or if patients reduce insulin independently due to reduced appetite. ADJUNCT ONE showed increased hyperglycaemia with ketosis events. Ketone monitoring is essential, especially during dose titration.
Risk of euglycaemic DKA if insulin over-reduced🩺 Clinical Practice Recommendations
- Off-label use only under specialist endocrinologist supervision — not for primary care prescribing in T1D
- Best candidates: adults with T1D + obesity (BMI ≥30) + insulin resistance + suboptimal glycaemic control on AID
- Insulin adjustment protocol: Reduce bolus insulin by 25–33% and basal by 10–25% at GLP-1 RA initiation
- Further 10% insulin reduction with each GLP-1 RA dose escalation
- Mandatory: Provide blood ketone testing strips and educate patient on sick-day rules / DKA prevention
- Continuous glucose monitoring (CGM) essential — do not initiate without CGM in place
- GI side effects similar to T2D population (~50% nausea rate at higher doses)
- Not recommended in T1D patients with low BMI, history of DKA, or erratic insulin administration
📚 Key References & Sources
He et al. JAMA Intern Med 2022; 182:513-519 (Gallstones meta-analysis) · Kanwal et al. JAMA Intern Med 2024; 184:1314-1323 (Cirrhosis/MASLD) · Yen et al. Clin Gastroenterol Hepatol 2024; 22:1255-1264 (Cirrhosis + T2D) · FLOW Trial — NEJM 2024 (Semaglutide renal outcomes) · Marso et al. NEJM 2016; 375:1834-1844 (SUSTAIN-6) · Bethel et al. Meta-regression of CVOTs for DR · Joo et al. Ophthalmol Sci 2024 (Cole Eye Institute) · Hathaway et al. JAMA Ophthalmol 2024; 142:732-739 (NAION) · EMA PRAC June 2025 NAION conclusion · WHO Safety Alert June 2025 · Simonsen et al. Diabetes Obes Metab 2025 (Denmark-Norway NAION) · STEP-HFpEF — NEJM 2023 · FIGHT Trial — Circ Heart Fail 2016 · ELAD Trial — Nature Medicine 2025 (Liraglutide in AD) · Cesta et al. JAMA Intern Med 2024; 184:144-152 (Pregnancy safety) · Dao et al. BMJ Open 2024 (Teratology services) · UKTIS Monograph 2024 · Shah et al. Diabetes Technology Society Consensus 2024 (T1D + AID) · ADJUNCT ONE/TWO Trials · UK Renal Pharmacy Group Guidance 2025